Projectile



Patented Feb. 3?, E925.

entree stares FRANK A. FAERENWdLD, G32 CLEVJQAND HEXGET$, .QIZLIQ.

E'o Drawing.

To all whom it may concern Be it known that l, FRANK A. FAHREN- wALn, a citizen of the United States, residing at Cleveland Heights, in the county of Cuyahoga and State of Ohio, have invented a certain new and useful Improvement in Projectiles, of which the following is a full, clear, and exact description.

This invention relates to projectiles, both those which are employed in hand fire arms, as rifles, and those which are employed in larger fixed pieces such as heavy ordnance, and has for its object to improve the construction of the same so as to increase the life of the barrels from whichthe same are fired. In all high velocity arms or ordnance it is necessary to use a jacket or driving band or hands to impart a rapid spinning motion to the projectile through engagcment with the spiral ribs and grooves formed on the interior of the bore. Lead is too soft and melts too easily, besides fouling the barrel interior very rapidly, especially when the same is made of iron or steel. Lead is employed for the bullets of hand arms owing to its high specific gravity, but to prevent it from becoming melted by friction it is, in high velocity arms, encased in a jacket of harder and less fusible material. In larger ordnance the projectile is usually of some kind of steel and is formed near its base with one or more external grooves which are filled with a suitable metal or alloy which shall engage the rifling and serve the double function of setting the projectile in rotation and preventing the leakage of gas therepast.

Lead is inapplicable to this use for the reasons above mentioned. Pure copper does not foul the bores, but is too soft for use in heavy ordnance, and when used for bullet jackets it becomes covered with a poisonous green coating by exposure to salt solutions and atmospheric conditions. In order to prevent this the expedient has been tried of coating this copperjacket with an outside layer of tin, which serves that purpose successfully but offers the disadvantage of fouling the rifle bore more rapidly than any other one thing; with the possible exception of nickel. ure soft iron (or a mild steel having a carbon content of less than two-tenths per cent) has been extensively tried, but produces excessive barrel wear.

The. object of my invention is the improvement of projectiles in respect to these Application filed December 15, 1919, Serial Ho. 8453382. Eeneweci 26, 29%.

jackets, or bands in such wise that they shall neither foul nor become corroded upon exposure, that they shall be soft enough to take the riding and also strong enough to set the projectile into rotation, and shall not be of high intrinsic value; while further objects and advantages of my invention will become apparent as this description proceeds.

l have discovered that the fouling effect of such a jacket or band upon the barrel is in proportion to 'its affinity for the metal of which the barrel is made, or'in other words to the ease with which itwould alloy under ordinary conditions with the metal of the barrel, which alloying tendency is peculiarly stimulated under the conditions of high ressure and high temperature and close rictional contact. Thus nickel which is one of the worst offenders in this regard is a metal which alloys with iron with par t-icular ease. Tin likewise is easily comerode the barrel, nor- 'bined with iron; while the high rate of wear noticeable when iron guiding bands are used is apparently due to the same alloying but in this case the metal is abstracted from the bore rather than from the projectile.

It is therefore necessary to employ for this purpose some metal which alloys with the barrel material only with difiiculty if at all and I have discovered that in the case of an iron or steel barrel all the advantages sought b this invention can \be obtained and all tie disadvantages present in previous attempts can be avoided by the use of certain alloys of aluminum or an aluminumlike metal.

Pure aluminum is for many purposes deficient in mechanical strength and hardness and also has too low a melting point, but commercial aluminum, containing as it does up to two or three per cent of various hardening metals in the form of impurities, of which iron and copper are the chief, will serve most pur oses with great success. However, I pret r to employ the alloy of such metal with copper, and while it is perfectly possible to emplo an alloy containing a large proportion 0 aluminum with a small proportion of copper, I prefer to em ploy an alloy containing a comparatively large amount of copper and a small amount of aluminum or aluminum-like metal.

My preferred roject-iles are made, particularly for big velocity arms and 0rdnames, with jackets or bands consisting of copper alloyed with from about one per cent to about seven per cent of an aluminum-like metal (aluminum or magnesium or both). Even so small an amount of aluminum or magnesium as one per cent when alloyed with co per changes markedl the appearance of t e metal, increases its ardness and resists its corrosion. Above about seven r cent of copper or magnesium the alloy mes too hard for most purposes. In case other hardening metals such as manganese, iron, nickel, or cobalt are present in any degree, it is necessary to decrease the amount of aluminum or magnesium, since the heavy metals have a disproportionate effect upon the properties of hardness.

For a second com ition falling within my invention but shghtl less desirable, I employ aluminum from a out 99% to about 93%, the balancebeing either pure copper or manganese, iron, nickel, cobalt, or some I a a 10y of less than about 5% of the barrel substance appears to be too great a dilution to lead to combination.

As a third modification I may employ from about 99% to about 92% of aluminum with the balance of magnesium, which is satisfactory as regards its hardness and strength, but is not as well considered be-' cause of its very low s ecific gravity. For the same reason all t e alloys containing and 64.

with the aluminum in all cases, the total amount of magnesium being in all instances maintained at less than about ten per cent of the whole alloy.

It will be understood that the alloys containin the lar er proportions of aluminum, in ad ition to. in unduly light in weight will be too fusible or some purposes where extremely high velocitiesare used, since all these high aluminum alloys are more fusible than aluminum itself; however, the alloy with co er, by' reason of its smoothness and wel nown lubricating qualities ofl'sets to some extent this low me ting point. The low aluminum, high co per alloy has no drawbacks whatever an further possesses an inherent smoothing and lubricating quality which is very beneficial to the arm.

Having thus described my invention, what I claim is 1. A projectile for firearms having a surrounding band or jacket made of an alloy of aluminum together with from about 1% to about 8% of a hardening metal having an atomic weight between and 64.

2. A projectile for firearms having a surrounding band or 'acket made of an alloy of aluminum and etween 1% and 8% of copper.

3. A jacket or driving band made of an alloy containing aluminum with about 1% to about 8% of one or more hardening metals having an atomic weight between 55 In testimony whereof, I hereunto aflix my signature. V

FRANK A. FAHRENWALD. 

